This invention relates to pumping systems and more particularly to pumping systems that draw samples from a source of liquid.
It is known from U.S. Pat. No. 4,415,011 to Douglas M. Grant, issued Nov. 15, 1983, and from U.S. Pat. No. 4,660,607 to Carl D. Griffith, issued Apr. 28, 1987, to pump liquids from a liquid source through a peristaltic pump into sample containers. In such system, the liquid is pumped through a flexible tube, the location of the liquid in the tube is sensed and it is metered into sample containers. The tube is subjected to flexing by rollers at a rate intended to deposit a predetermined sample volume into preprogrammed containers arranged in a sample tub. A distributor may move a nozzle over the appropriate sample bottle to deposit the sample therein. The distributors usually follow one predetermined path.
In the prior art samplers of this type, the peristaltic pumps are generally mounted horizontally with a horizontal axis of rotation for the roller assembly and fasteners such as bolts or screws must be removed to obtain access to the interior of the pump. The distributor only follows a continuous path and stops at mechanically fixed positions to deposit samples. Equipment used for triggering the taking of samples such as flow meters in stand alone equipment for such measurements.
These prior art samplers have several disadvantages such as for example: (1) under some circumstances, the tubes may travel laterally out of position within the peristaltic pump, resulting in a decrease in efficiency and increase in wear on the tube; (2) the pump may be unable to pump at the desired flow rate when there is a large head of pressure; (3) the tube within the pump may be subject to excessive wear; (4) it is difficult to change the peristaltic pump tube; (5) there may be occasions in which the outlet port of the sampler does not align in a satisfactory manner with the container to provide liquid therein; (6) there is insufficient flexibility in the movement of the distributor; (7) the samples may under some circumstances be tampered with to avoid detection of of some water conditions; and (8) the equipment used in cooperation with the sampler is excessively bulky and expensive.
Accordingly, it is an object of the invention to provide a novel liquid sampler.
It is a further object of the invention to provide a novel pumping system.
It is a still further object of the invention to provide a pumping technique which provides higher average line velocity under a head of pressure.
It is a still further object of the invention to provide a pumping system that permits easy changing of tubes;
It is a still further object of the invention to provide a peristaltic pump in which the tubes within the peristaltic pump have a longer life;
It is a still further object of the invention to provide a sampler which is able to deposit samples at random time intervals in containers in order to avoid tampering;
It is a still further object of the invention to provide a sampler having a distributor for distributing samples into bottles in which the resolution of the position of the distributor is accurately programmably controllable;
It is a still further object of the invention to provide a sampler in which different modules such as bubbler modules or data processing modules may be attached;
It is a still further object of the invention to provide a novel sampling technique in which better registration of the outlet nozzle with the sample container is provided.
In accordance with the above and further objects of the invention, a sampler includes: (1) a peristaltic pump that is mounted horizontally with a vertical axis of rotation of the roller assembly for easy insertion of pump tubing, has a tube aligning system to reduce creeping and peristaltic pump tube wear, a pump tube through which liquid is drawn at a higher average velocity, particularly when the speed of pumping cooperates with the pump tubing energy of restoration; (2) a distributor that has improved registration with containers to receive samples from the pump; and (3) is able to deposit samples in bottles having random time intervals under program control for security reasons.
The peristaltic pump housing is mounted to rotate the rollers in a horizontal plane about a vertical axis. One side of the pump housing is opened easily to expose the rollers for easy insertion of tubing. The rollers are designed with guides to avoid moving the tubing out of position and in one embodiment, are spring biased against a platen to avoid crushing the tubing. A safety check is provided by a magnet and reed switch to prevent the pump motor from operation when the pump housing is open.
The tubes are specially constructed to cooperate with the pump motor for maximum efficiency by utilizing a speed and energy of restoration that maximizes vacuum force on the liquid. For this purpose, the hose is specially cured for stability and a thickness is selected to provide a coefficient of restoration that increases the vacuum pressure. The pump is operated at a speed in which the energy of restoration is sufficient to restore the shape of the tube between compression at relatively high speed and may pull water under a twenty-four foot head with a velocity of two feet per second. The housing accommodates modules connected to sensors for transmitting sensed values and for recording them.
In operation, the nozzle of the distributor is adjustable in position and may be programmed with precision to register with bottles of different sizes and at different locations. For zeroing, the distributor is moved in a first direction against a stop and then rotated in the opposite direction to press against the stop from the opposite side. The play between the two caused by pressure against the stop is measured and utilized to provide a zeroing function from the distributor and thus permit greater accuracy during distribution. The distributor includes a coded pulse generator that generates pulses in accordance with its movement among the bottles to have in memory an exact indication of where it is located. In that manner, the program may control the location of the outlet of the distributor hose to time the depositing of samples even though different arrangements of bottles may be used in the same container.
The sampler includes a random number generator so that samples will be taken at random times. The pattern is stored in memory. This prevents tampering with sample times by personnel working at a site in which monitoring is taking place. Standard bottles with standard samples may be included so that, if tampering occurs with the sample bottles, it may be detected by interrogating the memory to determine when samples were drawn from the body of water and into which containers they were deposited and which samples or sample bottles should have standard solutions or no solutions in them. Moreover, the software can be drawing and inserting one set of samples in containers according to one program and nonetheless simultaneously follow at least one other program. The other program or programs may be triggered during the first to start program such as by the detection of a programmed pH or flow rate.
From the above description, it can be understood that the pumping system of this invention has several advantages, such as for example: (1) it permits higher average pumping velocities under high head conditions with peristaltic pumps; (2) it provides longer life to peristaltic pump tubes; (3) it increases the life of tubes and reduces lateral movement; (4) it permits more precise positioning of the distributor outlet port; (5) it permits easy attachment of modules for cooperation with the sampler; (6) it permits safe and easy access to the pump tube for replacement thereof; and (7) it provides a security system to avoid tampering with samples.
The above noted and other features of the invention will be better understood from the following detailed description when considered with reference to the accompanying drawings, in which:
FIG. 1 is a block diagram of a pumping system in accordance with the invention;
FIG. 2 is an exploded perspective view of a sample collector using the pumping system of FIG. 1 in accordance with an embodiment of the invention;
FIG. 3 is a partially exploded, perspective view of a liquid sensing device used in the embodiment of the invention shown in FIG. 1;
FIG. 4 is an exploded perspective view of a liquid sensing device used in the embodiment the invention shown in FIG. 1;
FIG. 5 is an elevational sectional view of a portion of a liquid sensing device used in the embodiment of the invention shown in FIG. 3;
FIG. 6 is a fragmentary, exploded perspective view of the liquid sensing device and pumping system used in the embodiment of the invention shown in FIG. 1;
FIG. 7 is a fragmentary simplified perspective view of an embodiment of a sampler broken away to show a distributor and a bottle tub useful in the embodiment of FIG. 2;
FIG. 8 is an exploded fragmentary perspective view of a pump, sensing section and distributor useful in the embodiment of FIG. 2;
FIG. 9 is a fragmentary top elevational view of a portion of the sensing section of FIG. 8;
FIG. 10 is a simplified, fragmentary perspective view of a pump roller assembly in accordance with the invention;
FIG. 11 is a simplified perspective view of an embodiment of pump and sensing system;
FIGS. 12 and 13 are simplified fragmentary perspective views of two other embodiments of pumping systems;
FIG. 14 is a schematic drawing of an air bubbler module in accordance with the invention;
FIG. 15 is a schematic diagram of the container full detection system;
FIG. 16 is a block diagram of a portion of the pumping system of FIG. 1;
FIG. 17 is a block diagram of a portion of one of the embodiment of FIG. 16;
FIG. 18 is a flow diagram of a portion of a prgram used to operate the sampler of FIG. 2;
FIG. 19 is a flow diagram of a portion of the embodiment of FIG. 18;
FIG. 20 is a flow diagram of still another portion of the embodiment of FIG. 18;
FIG. 21 is a block diagram of still another portion of the embodiment of FIG. 18;
FIG. 22 is a block diagram of another portion of the program of FIG. 18;
FIG. 23 is a flow diagram of a portion of still another embodiment the program of FIG. 18;
FIG. 24 is a flow diagram of a portion of the program segment of FIG. 18;
FIG. 25 is a block diagram of still another portion of the embodiment of FIG. 8;
FIG. 26 is a block diagram of another embodiment of FIG. 18;
FIG. 27 is a flow diagram of another portion of the embodiment of FIG. 18;
FIG. 28 is a block diagram of another portion of the sampler of FIG. 2; and
FIG. 29 is a block diagram of still another program useful in the embodiment of FIG. 2.